With the 3lt V6 Turbo Diesel R51. Ti550. I average about 9.6 liter/100 km = 24.50 mile/gallon (US) But the best I've ever seen it is 7 liter/100 km = 33.60 mile/gallon (US). That was cruising, down a highway behind a freight truck. Towing at a little over 3 Ton, I got 14 liter/100 km = 16.80mile/gal...